Power plants, gas turbine engines and other heat engines using the Brayton cycle can benefit from heat exchangers. In SCO2 Brayton Cycle exhaust gases are reused at the intake, and thus, form a closed or semi-closed system. A recuperator may be used as a heat exchanger in such systems and may operate as a counterflow energy recovery device. The recuperator is usually positioned within the supply and exhaust air streams to recover waste heat and increase the overall efficiency of the SCO2 Brayton cycle. The gases are pre-heated using the recuperator to transfer waste heat from the exhaust and to the compressed air, which is preheated so less fuel is required for heating the gases to a turbine operating temperature. In a closed or semi-closed Brayton cycle recuperator, the working fluid such as CO2 is recirculated. The air expelled from the turbine is reintroduced to the compressor. The heat exchanger as a recuperator pre heat the working fluid before it is introduced to combustion chamber. Some systems may include a high temperature recuperator and a low temperature recuperator.
Some power generation systems use supercritical carbon dioxide (S—CO2) as the working fluid. It is desirable in some of those systems, for example, using the current heat exchangers in some conventional power plants, to scale the systems without disrupting the long-term operation of the system. Many heat exchangers as recuperators are not easily scalable and are used in moderate temperature and pressure ranges, and therefore, are not robust. To scale up a current heat exchanger in some power plants would disrupt the entire system.